Chords of Progression
by dyingimmortal
Summary: AU: In which Levi becomes a teacher and there is a lot of music theory. Rivetra. Sequel to Perfect Harmony.


_Sequel to Perfect Harmony (posted on my profile)__. You should read that first if you want to read this, but if for some reason you don't want to but still want to read this, just know that Levi plays piano, Petra plays violin, and they met when they performed together._

_I don't know if this makes much sense to people unfamiliar with music theory terms; I tried to explain things but idk. Like seriously, this fic ended up being almost like a theory lesson. And theory is terrible. And the structure of this is also terrible. And this is cheesy and clichéd as all hell. Oh well, you've been warned. More notes on this fic at the end._

* * *

Levi's not sure how she wormed her way into his life.

He's always been a bit of a loner: people who know him for his playing admire him from afar, then recoil and stay away once they really get to know _him_—him, not his music. He knows perfectly well he is generally a rude person, someone who can't keep his mouth shut when he should, someone whose sense of humor leaves most people blinking awkwardly as they try to think up proper responses to his shitty jokes.

Levi knows himself very well, knows that he is not a friendly or nice person, but the world disgusts him enough that he can't bring himself to care. Hanji understands and is able to deal with him, Erwin for some strange reason likes to spend time with him, and he has his Steinway grand piano and fast Internet on his computer, and that is enough.

He doesn't know how Petra got into the picture.

He's played for many people before, but none of them quite like her. It's not just how she doesn't seem to mind his… unique personality (he will freely admit that it is crappy) or how she puts up with all the shit that comes out of his mouth (there is a lot of it); it's not even how she plays, all bright and buzzing and happy as her fingers fly over the strings, her heart completely given to the music.

No, Petra is just different from all the other musicians he's met over the course of his career, and she has somehow gone from being one of the many violinists he's played for to just another aspect of his life.

Which is why she is lying across his bed, booted feet dangling off the edge (he still has _some_ requirements), and he has not kicked her off yet.

"Oh, look at this!" she exclaims, waving her phone in the air. The screen's backlight shines on her face, giving her skin a pale white glow. "The Tokyo Quartet's performing upstate next week; it's one of their last runs before they disband. It should only be an hour's drive if we can avoid the traffic; you wanna go?"

"I've seen them before," Levi says. He sits at his desk, ignoring the computer on it in favor of the tablet on his lap. He has three new emails from Hanji marked "urgent," though Hanji's definition of "urgent" can vary from "I'm in the hospital with a broken leg" to "I just discovered the best recording ever of Mozart's bassoon concerto, Levi, YOU HAVE TO LISTEN TO IT."

"They're playing Beethoven's fifth string quartet in A."

"I've heard it before."

"By the Tokyo Quartet?" Petra sounds skeptical.

"I don't remember. I don't like string quartets much," Levi says. He opens the first email and is bombarded with JPEG files of two children.

"You take that back," Petra says with a gasp. "String quartets are the _bomb_."

"If you say so."

"I've played that piece before when I was still in school; the members of my string quartet are awesome. Hey, I should introduce you sometime; Erd's off-season right now—he plays viola with the Chicago Symphony—and I think he's in the city. I'd love to introduce you and—who are those kids?"

Levi frowns as he scrolls through the pictures; couldn't Hanji have sent him the text before the images? "I don't know." There is a black-haired girl with Asian features and a dark-haired boy with bright green eyes featured in most of the shots, both of them on the piano.

Petra has hopped off his bed and is now standing by his chair, leaning over his shoulder. He tries to ignore the whiff of her shampoo he gets—her hair smells like lavender and lilacs. "Why are they in your inbox?"

Levi finally reaches the text buried under all the photos. "The girl's a piano prodigy and the boy… is not bad, and he works hard. They're adopted siblings, and their mother's been looking for a new piano teacher for them. Oh. Hanji wants me to teach them."

"They look like sweet kids," Petra says. She eyes the picture on his screen: the boy and girl sitting on a piano bench, the boy smiling widely and the girl merely staring, unimpressed, at the camera. There is a red scarf wrapped around her neck.

"They look like brats."

Petra pokes him in the shoulder. "Hey. I bet _you _were a brat when you were a kid. Way brattier than them."

"I was, actually. The shittiest brat of them all."

She laughs, and the sound is light and carefree, the sound of sunshine, the opening chords of Vivaldi's "Spring." Levi tries to ignore the thought.

"So are you going to teach them? Have you actually taught before?"

"A bit," he says, "though I'm no good with kids. I haven't had any long-term students before." He flicks to the second "urgent" email; this one is just text. "Their mother wants them to learn theory and eventually composition too—weekly lessons, one practical and one theory every two weeks."

Petra wrinkles her nose. "Ugh. Theory."

"Music theory is an essential part of becoming a well-rounded musician."

"Well, of course _you'd_ like theory." She rolls her eyes. "It's precise. Mathematical. _Clean._ Just like you."

"And of course you'd hate it. You just feel everything and don't bother with any analysis."

"It's why I decided not to pursue a doctoral degree," she admits. "Theory class was the bane of my existence in college." She snorts. "It doesn't help me with performance anyway."

The third email is all exposition; Hanji explains in detailed points why Levi should take these students. They have clear talent; Hanji's heard the girl play and she is excellent ("she reminds me of a cuter, less constipated-looking little-girl version of you, Levi" are her exact words); their mother is offering to pay a lot for two hours of his time once a week; they live in the Bronx, which is not too far from Levi's apartment in Westchester (though they'd drive to him for lessons and not the other way around, so he fails to see why Hanji thinks this is a valid point).

Petra is reading the email too over his shoulder and he wonders why he doesn't mind; he usually hates people reading anything over his shoulder. She lets out a low whistle when she sees the offered sum for his services. "Sounds like a good deal to me. You haven't been doing anything recently, have you? No upcoming concerts?"

"No," Levi says. Other than the Saturday night concerts he does a few times a month and the two other performances he did with Petra a few months ago, he hasn't been busy. He's been working on recording all of Beethoven's piano sonatas, but he's in no rush to finish them.

"So you'll teach them?"

Levi goes back to the first email; there is also an MP3 file attached to it. He hits 'play' and the file downloads before opening in a separate app, quiet notes playing from his speakers. He recognizes the piece instantly; "Für Elise."

"This is played by… the girl?"

"The boy," Levi says, checking. "Eren Jaeger." The kid presses too hard on the keys, especially since the beginning of the piece is meant to be light rather than solid, but his musical phrase and direction are apparent, and there is potential in his playing. "They're eight years old; the girl's only played for a year but the boy's been playing for two years."

"He's decent," Petra says. "You know I played piano too when I was a kid; compared to this I sucked."

"You still suck."

She punches him in the arm. "I'm still better at piano than you are at violin, so shut up."

"Yes, but piano is your minor. I've never played the violin before in my life."

"Shut up anyway."

His phone buzzes and Levi picks it up. It's a text message, just three words: "I'm coming up."

He drops his phone back onto the table and pauses the recording. "Erwin's here."

Petra scrambles to her feet, grabbing her bag by the desk and slipping her phone into her pocket. "I should go then. It's getting kinda late anyway, and I told Rico I'd go shopping with her tomorrow. I haven't hung out with her in a while."

"Erwin doesn't mind. You can stay a bit longer," Levi offers, but she shakes her head.

"No, it's nearly nine. I'll see you next week, maybe? Tokyo Quartet?"

Levi wasn't lying when he said he didn't like string quartets much; perhaps he's just too used to the sound of his own instrument, but he doesn't like polyphony and other arrangements if they don't involve the piano or a full symphony orchestra. Chamber music—violin duets, string quartets, woodwind quintets—has never done much for him.

But Petra is waiting for an answer, her eyes bright and hopeful, her smile warm and inviting, and he's probably being an idiot again, listening to his stupid all-too-human heart instead of his logical mind, but he finds himself saying anyway, "I'll call you."

She beams, her nose crinkling in happiness, and his so-called logical mind thinks it's one of the cutest things he's ever seen.

.

.

.

Petra's only been gone for two minutes when Erwin steps into his room. The flutist is impeccably dressed as usual, his hair neat, face serene, designer shoes clicking on the hardwood floor as he shuts the door.

"Did you steal my spare key again?" Levi asks, not looking up from his computer, which he opened to type his response to Hanji.

"Just because you left it out in the open for people to take doesn't mean I _stole_ it," Erwin says.

Stupid bastard. "You're off-season again? Why don't you go visit your mum, old man?"

"I was driving by and thought I'd stop in."

"You mean you thought Hanji was around?"

Erwin ignores the insinuation. "I just ran into Miss Ral at the front door; you've been spending quite a bit of time with her recently, haven't you?"

Levi scowls. _Two can play that game, huh?_ "Not really."

"You know, Levi, you can be quite stubborn sometimes. It's not that hard to ask a girl out."

"I don't want to ask her out."

Erwin makes himself comfortable on Levi's piano bench—only Erwin could make sitting on a hard bench look comfortable. "Denial isn't healthy."

"You're one to talk. Don't think I don't see you staring at Hanji whenever she's here."

It's like speaking to a wall; no, a wall would probably have more of a reaction. Erwin merely folds his hands across one knee and continues like Levi hasn't even spoken.

"Well, if you're not going to ask her out, then what are you going to do?"

"She's my _friend_," Levi says tersely, but even as he says the words he realizes their weight. He's never been one to make friends easily, not at all—his whole life has been filled with acquaintances, but hardly ever friends. He's known Hanji for years and years and Erwin almost as long, and they were the only two people he would truly think of as friends.

_Were_—because now Petra is the third.

"I'm your friend, and I hardly ever see you."

Levi rolls his eyes because anyone else saying that would sound petulant; Erwin just sounds like he's stating a fact, same as _I play the flute_ or _The name's Smith. Erwin Smith_ (Levi will never admit it, but he likes James Bond movies. A lot).

Before he can respond, Erwin nods at his computer screen. "Are you going to take those students?"

Levi squints suspiciously at him. "How did you—you've been talking to Hanji again, haven't you." He should have known. "She hasn't said anything to me recently either. You finally making a move, old man?"

"Well, are you taking those students?"

"I'll think about it."

He turns back to the computer, ready to tell Hanji to stop spamming him with kid commercials, but Erwin suddenly stands up and walks over to his desk, leaning over his shoulder to read his reply, and Levi stops typing to look up and glare: he'd never consciously think something so cheesy, but Erwin really is a good friend—but that still doesn't give him permission to look over Levi's shoulder at his computer screen.

_You let Petra_, a little voice that sounds an awful lot like Hanji points out.

Levi tells the voice to shut the fuck up.

"I think you should give these children a chance," Erwin says, moving back easily like it's not Levi's pointed glower prompting him to do so. "I think you'd be surprised."

"It has nothing to do with their skill level. I hate kids."

"All the more reason to teach them. You'll need some experience so when you have your own, they'll be easier to deal with."

Levi, in the middle of typing Hanji's name, twitches and his fingers spasm across the keyboard for a moment, turning "Hanji" into "Hansdlf." "Where the fuck did that idea come from?"

He knows his mother has always wanted to have grandchildren and part of him regrets she never got the chance to see that wish fulfilled, but for the most part, he has never thought about children before—hell, he's never even thought about marriage. Most women he meets get on his nerves quickly, and who in her right mind would want to deal with him for the rest of her life?

There is a glint in Erwin's eye that Levi finds particularly shifty, but then it disappears and the flutist raises an eyebrow and says, "Give them a chance; you won't regret it. Think about it, Levi: when have I been wrong before?"

"You're shitting me."

When he gets no response once again, Levi shoves away from the computer desk to walk over to his piano, a German-made Steinway D-274 he bought five years ago to replace his mother's, which is now collecting dust in the living room of her house. When she passed away, Levi threw himself into his music in order to escape any too-raw emotions he had, because emotions are stupid and messy and he has always hated them, but he needed a new piano that didn't remind him of her all the time.

He pushes the lid back and runs his fingers over the keys, the smooth ivory as soothing and familiar as someone else's warm bath or lover's touch. His fingers still and he stares at them for a moment, because he always feels so twitchy when they aren't moving: it's only when they're resting on a keyboard that he never feels the need to do _something_ with them; all he has to do then is play.

He runs through a few quick warm-up scales and thinks the kids Hanji wants him to teach probably already know these. They've definitely got basic arpeggios down too; he could start off with some finger exercises to see how solid their fundamentals are…

"I'll tell Hanji your answer," Erwin says, pulling out his phone. "She'll be delighted."

Levi scowls. "I'm getting tired of Beethoven's piano sonatas anyway."

"Of course."

.

.

.

The two children look exactly like they do in the pictures: Eren Jaeger is full of life, bouncing on the balls of his feet eagerly, eyes gleaming with anticipation as Levi sits him down at the piano in the living room and asks him to play a C major scale.

Mikasa Ackerman, on the other hand, sits quietly on the couch with her adoptive mother, her back straight and eyes fixed firmly on Eren. She has that red scarf from the photograph wrapped around her neck, pulled up to hide her mouth and part of her nose; she clutches it like she doesn't know what else to do.

Eren's foundations are a bit shaky but undeniably there; his hand posture is correct and even if his nails are too long for a piano player, his control over his fingers is adequate and his technique is relatively stable. His rhythm is not bad either, and with hard work, Levi's sure the boy will make it far.

Mikasa, however, is undeniably gifted; her technique is flawless, her rhythm precise, her dynamics well played, her musical phrase mature and sophisticated. Levi would find it hard to believe she's only played for a year, but he remembers being the same level or better when he was half her age, so instead he finds faults with her playing.

She has feeling and direction, but it is vaguely empty, like she doesn't feel the music in her heart. That's the most important characteristic of a musician in Levi's opinion: anyone can practice until his fingers bleed and his technique is perfect, but what he plays are only notes unless they're _felt_; then the notes become music.

Which, if he stops to think about it, is funny, because he hates feelings—but even though music is all about emotions, it portrays them much differently from the messy human ones that still thump around his heart. All humans have emotions, and Levi ultimately prefers pouring them into his playing than spilling them all over the place.

He revises his plans for the children's lessons after the first one; Mikasa is much more advanced than he expected and Eren needs to work more on the strength in his fourth and fifth fingers. As for theory lessons, Levi wouldn't be surprised if Mikasa has perfect pitch, which would make the learning process a lot easier, but he doesn't know if either kid has any basic knowledge of the subject yet.

Levi cracks his knuckles and sighs, then minimizes the Word document and opens World of Warcraft instead. He hasn't played in a while and maybe Hanji is online; she owes him a rematch.

.

.

.

When the Jaegers arrive for their lesson next week, Petra is already there, her feet propped up on his coffee table (shoes off, of course), texting her friends and flipping through a Shar music catalogue. She sits up with a start when the doorbell rings.

"It's fine," Levi says, standing up from the piano bench. "It's the kids I told you about."

She frowns at him. "It's _not_ fine! You should've told me they were coming over; it's rude to have people over when you're going to teach." She makes a face. "You at least turn your phone off during lessons, right?"

He doesn't, actually, but he supposes that's not the point. He knows he lacks basic etiquette in many areas, and he usually doesn't care one bit, but something about the disappointed way Petra is looking at him makes him feel somewhat dismayed, like he did something wrong instead of acting the way he always does.

"You can go to my room then," he says, heading towards the door. "Just shut the door and don't make any noise."

"You're lucky I don't have anything to do tonight," she sighs, "or I'd be so pissed at you right now." She flicks him on the shoulder as she walks past, but she also smiles and his stupid heart does something weird in his chest.

He opens the door and lets Carla Jaeger and her two children in; they are all bundled up against the early autumn chill, complete with hats and gloves and of course, scarves. It's funny how the doorman, Moblit, always knows when to ask if Levi wants someone to be let up or not, and when not to ask. He thinks it's mostly due to Hanji's influence.

"So you'll be starting them on theory today, Mr. Stolze?" Carla says as she seats herself on the couch—luckily not where Petra was sitting, because that part of the couch is probably still warm. "My husband told me an early foundation in music theory is very helpful for the later years."

He nods and shoves his hands into his pockets. "We can go to the dining room."

Eren races there, his staff paper already out of his backpack, clearly enthusiastic to begin. Mikasa plods along behind him dutifully.

Levi grabs his binder off the top of the piano and follows them, making a mental checklist of things to cover and things to review—they probably already know a decent amount of basic theory like note names and meters and intervals and perhaps chords, but if their mother wants them to learn _composition_ then he's eventually going to have to teach them figured bass and cadences and four-part harmony and chord progressions and counterpoint and how to analyze musical forms and _dammit, _why did he agree to this?

He silently curses Erwin and Hanji for ganging up on him and presses his fingers to his forehead, willing his surely murderous glare away. When he removes his hand, he sees his two new students staring up at him from the dining room table, Eren with excitement and Mikasa with apathy.

_Alright, brats,_ he thinks, cracking open his binder to look at his hastily scrawled lesson plans. "Get out your pencils. I'm going to go through a quick list of terms to see what you're already familiar with; whatever I say, you write down what you think it is." Mikasa already has a pencil out so Levi forges on; Eren can catch up. "One: subdominant..."

.

.

.

Two hours later, Levi has a certifiable headache as he waves off Eren's constant stream of questions, accepts Carla Jaeger's payment, and bids the family a good evening as they step out the door. He should probably wish them a safe drive home too (Hanji's taught him well) but his politeness has its limits, especially when he feels agitated enough to play Rimsky-Korsakov's _Flight of the Bumblebee_ as fast as he can. Twice.

He pushes open the door to his room and finds Petra rummaging through his closet, up to her elbows in his vast collection of white dress shirts. She emerges from the closet and gives him a little wave when she sees him.

"Finally done? I've been bored out of my mind so I tried to organize your clothing for you—I always do this for my dad when I visit him—but your closet's even neater than mine. Also, you need to wear something other than black and white and jeans."

He doesn't say anything, just sits down at his desk and opens his computer. He should probably feel annoyed that she was looking through his things, but he finds he somehow doesn't mind. Again.

Trying not to dwell on why, he checks to see if Hanji is online. She is, so he immediately sends her a message: _How long have you been seeing Erwin without telling me?_

"So how was the lesson?" Petra asks, plopping down on his bed.

"It's hard to teach them together," Levi says, tapping his fingers against his keyboard as he waits for a reply. "Eren's played piano longer so he's more familiar with scales and intervals, but he doesn't know how to name them properly yet. Mikasa's a fucking sponge."

Petra chokes a little, giggles and spreads a hand over her mouth as if holding back more laughter. "Oh my god, you just called someone a _sponge_. I think you should avoid metaphors, Levi."

He scowls at her. "You know what I mean. She already knew her basic scales and triads and meters and all that crap, but she just breezed through everything I threw at her and I got her started on seventh chord inversions. In under _two fucking hours_."

Petra lets out a low whistle. "That sort of brain could've helped me when I was still in school. Theory was my worst subject."

His computer _dings_ as Hanji's response comes through. He checks the window to see: _I have no idea what you're talking about. How were your students this time? I bet Petra's with you too, tell her I said hi!_

Levi hasn't felt the urge to smoke for a while now, but whenever he gets particularly irritated or stressed, the itch to stick a cigarette in his mouth comes back. He rummages through his desk drawers, finds another unopened pack of gum (they've replaced all his packs of cigarettes by now), and shoves a piece in his mouth.

"Hanji says hi," he says.

"Tell her I said hi too!" Petra flops over on her stomach and props her chin on her hands. "And that we should hang out again sometime; the heels I got at that place she showed me last time were—" She breaks off mid-sentence and hops off his bed to stand next to his chair, original thought forgotten. "I've decided. I'm going to take you shopping, Levi. You need new clothes."

He blinks. "No I don't."

"Yes you do. I just saw your closet."

"It's filled with clothes."

"I'm counting all your white dress shirts as one article of clothing because they all look _exactly the same_."

"They're different brands—"

"Doesn't matter. When's the last time you went shopping?"

He bought three different recordings of Liszt's La Campanella on iTunes yesterday, but that's probably not the sort of shopping she's referring to. He racks his brains for a concrete answer and realizes the last time he can say for sure is—

"Around my birthday," he admits.

Her eyes widen. "Your birthday's on Christmas and that was _nine months ago_. That's it. I'm taking you shopping next chance we get."

"I don't need to go shopping."

"Yes you _do_. Aren't you bored of wearing the same thing every day? I always thought you just wore black and white because you felt like it but it turns out you don't _own_ anything else."

"I don't need anything else."

"Come on," she says, and there is a little smirk at the corners of her lips, a spark of playfulness in her eyes. "Don't tell me you're another one of those guys who can't stomach a little bit of shopping. I had higher expectations for you."

Why does any sign of disappointment—even the most indefinite, teasing sign—from Petra make him feel like a complete ass? He's not even sure why he's so against it, just that he hates spending money on clothes when he could buy more useful things. (_Like World of Warcraft expansion packs? _his mind supplies.)

He mentions this (not the World of Warcraft part, of course) and she sighs, crossing her arms over her chest. "Well then, I'll take you shopping on… huh, Labor Day just passed… it's two months away, but Black Friday then, okay? There are sales everywhere so you won't be spending nearly as much. I'll even take you to an outlet mall or something for even more savings. No protests. You have no choice."

Levi opens his mouth, then closes it again. To his surprise, he finds he doesn't _want_ to protest anymore; it's pathetic, really, but he doesn't mind if he gets to spend more time with Petra.

_You dumbass, _he tells himself, but what he says is, "Fine."

She grins, and he tears his eyes away from her face before his heart decides to do something ridiculous again like join his fingers in wanting to play _Flight of the Bumblebee_.

.

.

.

His students improve quickly—especially Mikasa, whose progress is immense. He still needs to coach more feeling out of her; she needs to pay more attention to the subtlest details, but she deserves the title of prodigy in every respect.

Levi has never seen a more hardworking student than Eren Jaeger. What the boy lacks in skills he makes up for in sheer resolve; he is frustrated when he can't get something right, but he never stops trying, and he has so many questions about everything Levi doesn't know if he wants to tell the boy to shut up or give him candy or something for being so passionate about… everything.

In all honesty, Levi doesn't like music theory either, but he finds it necessary (or at least helpful) to know as a musician so he never complains about it. Eren seems to enjoy it, though he still mixes up his scale degrees sometimes—"The supertonic is the _second_ note in a scale, not the seventh; the seventh is the _leading tone_," Levi has to tell him multiple times. "It's called the _leading tone_ because it is the seventh note, the last unique note of the scale before it _leads_ back to the tonic—what's the tonic again, Mikasa?"

"The first and last note of a scale; the distance between the notes form an octave," she will answer like she's reciting from a textbook, and Eren will give her an annoyed look before nodding at Levi and circling the problem in his notebook.

Mikasa moves on from seventh chords to nonharmonic tones and cadences and basic analysis. Whenever Levi feels particularly lazy, he will print off a worksheet of common chord progressions from the Internet two minutes before she arrives and tell her to study it as he works with Eren; by the time he gets around to her, the worksheet will be done and she will be staring off into space, playing with the ends of her scarf (she never takes it off, even indoors).

Similarly, he never needs to spend too much time with her on the piano; she plays through her scales, her finger exercises, her etudes, then her piece, he gives her a few pointers, she does whatever he tells her to perfectly, and then it's Eren's turn. He will guide Eren through the notes, pointing out changes in dynamics and articulation, tapping his fingers loudly against the sides of the piano when the boy stumbles on the rhythm or accidentally starts slowing down or speeding up the tempo; he usually spends more time with Eren than Mikasa every week, but they both improve quite quickly, and Levi sometimes feels a strange flicker of something in his chest that just might be pride.

Near the end of November, he tells Carla Jaeger he wants to sign the two children up for a piano recital early December; he thinks they're ready. She agrees, so he does and immediately phones Hanji about it, knowing she'd want to know.

"Aw, you're such a good, responsible teacher!" she coos, and he glares before remembering she can't see it.

"Shut up, Hanji."

"No, seriously, what happened to hating kids? You always say you have no patience for them."

Levi drums his fingers against his desk and thinks about Mikasa's quiet obedience, Eren's blazing determination. "For a couple of brats, they're not that bad."

He tells Petra about the recital too, and she immediately says she'll go. "You've talked about them a lot in the last few months," she says, "and I totally want to hear them play."

"I haven't talked about them _a lot_."

"You mentioned them more than twice, which is a lot for you."

Well, that's true. Before he can say anything, she adds, "Black Friday's coming up. Don't think I've forgotten."

It takes him a moment to remember. "Oh. That."

"I'll come pick you up, since I'm supposed to be taking you shopping and not the other way around. What time's good for you?"

Levi checks his calendar and realizes Friday afternoon is when he has to go meet with the manager of the community center where the recital will be held. "… Morning?"

Petra groans. "Morning? Seriously?"

"I have business Friday afternoon."

"But then we'd have to rush back and—hang on, let me check something… oh yes, the outlets we're going to open Thursday evening for early Black Friday shoppers. You want to go then? We'll get back late and then you can sleep in and be ready for whatever you're doing in the afternoon."

"Sure," Levi says. He doesn't really care.

"You want to grab dinner together? The outlets I'm thinking of are in New Jersey; we can eat there. I'll pick you up at four, maybe?"

"Sure."

"Alright, it's a date! I'll see you then."

She hangs up and Levi stares at his phone for a moment. _It's a date,_ she said. He can't remember the last time any girl said that to him.

_You idiot. You know what she meant. Stop being such a damned fool._

He tosses his phone onto his desk and opens Netflix on his computer; he's already practiced for three hours today and he might as well waste some time.

.

.

.

Levi's never been to the Woodbury Commons Premium Outlets before, but he's seen other places like this and he recognizes most of the brands listed on the map near the parking lot. It's not even six yet and the place is already quite crowded with cars, families and couples and also many individuals come to take advantage of one of the biggest sales of the year.

They go to the food court first, where Levi eventually decides on pizza because he refuses to eat McDonald's and he doesn't want Chinese food either. Petra makes fun of him when he mops up the oil on his slice with a napkin.

"Even _I_ don't do that," she says, taking a big bite of hers. "You're such a girl sometimes."

He doesn't answer because he is staring at her fingers; she has a hangnail on her left pinky and it's driving him crazy. He rummages through his coat pockets and finds his nail clipper, and hands it to her without a word.

She looks at him, puzzled, then glances down at her hands and bursts into giggles. "You just proved my point! Who carries a nail clipper everywhere?"

He frowns at her, puzzled. "You play violin; you should know the importance of keeping your nails short."

"But I don't bring my nail clipper everywhere I go. I just leave it in my violin case."

"Well, I can't carry _my _instrument everywhere I go."

"Fair point," she concedes. "Uh, my hands are kind of greasy right now; you sure you want me to take that?"

He retracts the nail clipper quickly and she snorts.

"This pizza's good," she says, smiling. "Stop wiping the oil and just eat."

There is a small smear of tomato sauce on the corner of her mouth and he suddenly wants to reach across the table and wipe it for her. He quickly grabs his knife and fork and starts cutting his slice into small pieces before his fingers decide to grow a mind of their own and do something he'd probably regret.

"Loser," she says, but she's still smiling, and if she were Hanji or Erwin the conversation would probably devolve into a trade-off of friendly insults, but she's Petra so Levi just eats his pizza and doesn't say anything.

"So, the recital's next Saturday afternoon at two, right?" He nods. "And you texted me the location already. What are they playing?"

Petra's right; the pizza is surprisingly decent. He cuts another piece off the crust and puts it in his mouth, and chews and swallows before answering. "Mikasa's playing Beethoven's Sonata Pathetique and Eren's playing his Bagatelle no. 25 in A minor, 'Für Elise,' the piece he played before that Hanji sent me."

"Aw, that's cute. And wow, Sonata Pathetique already? The girl _is _talented."

"She's already doing four-part harmony," Levi says, "and she's having less trouble with it than I did at first. I almost never find mistakes in her work."

Petra pretends to gasp. "_You_, have trouble with something? Never!"

He shoots her an irritated look and she laughs into her drink, tilting her head up to down the last few sips of Coke. He finds his gaze catching on the slim outline of her neck and he averts his eyes quickly.

_You're such an idiot,_ he thinks to himself, drumming out compound meter rhythms on the table.

"And what's the boy doing, theory-wise?" Petra wants to know. "Please don't tell me he's doing counterpoint or something; I already feel bad enough about myself for nearly failing theory every year."

"I've got him started on some basic chord progressions, cadences, nonharmonic tones, stuff like that," Levi says. "His parents—especially his dad, apparently—really want to push him ahead so he's about the same level as his sister. He still has trouble identifying nonharmonic tones though; it's clearly a IV chord in C major and there's a B passing tone and he gets confused."

"Cut him some slack," Petra says. "Roman numerals confused the hell out of me for ages, and you've only been teaching him theory for… two months? And it's not every week either."

Levi shrugs. "I guess I'm just used to his sister; I barely say anything and she just gets it. Though Eren spends some of his time listening to me talk to her, so sometimes I try giving him his sister's worksheets to see what he grasps."

"And…?"

"None of his leading tones go to the tonic."

Petra puts a finger on her chin and looks up in thought. "If it's four-part harmony, then the leading tones don't _have_ to go to the tonic, right? If they're in the inner voices, and if they're consonant with the outer voices—"

"Yes, but _none of_ his leading tones go to the tonic. It's a common chord progression—in major keys, the goal of any chord progression is the tonic chord. I don't think he gets that."

"Ooh, I always had double leading tones in my harmonizations when I took theory," Petra says. "My theory teacher always got so pissed off at me. 'What is this? Another leading tone! If you make it go to the tonic, you'll have parallel octaves in your harmony! That's bad! If you don't make it go to the tonic, that's also wrong! Either way, points off!'" She shakes her head and chuckles. "Leading tones are so annoying. They're interesting, but they just stick out all over the place."

Levi thinks he is a leading tone then, a strange note in the scale, a leading tone chord without a tonic to go to. He sometimes even feels like a nonharmonic tone, a note that when not used properly definitely does not belong there, but he has Hanji and Erwin and now Petra to pull him back into the harmony, ensure he has a place there, however on the edge it is.

Petra seems oblivious to his thoughts; she glances down at her watch and huffs. "Crap, we spent way too long here. Let's go before the lines outside the stores get really long. Come on!" She stands up and starts to collect their empty paper plates and cups, getting ready to throw the garbage away on their way out.

He takes the trash from her and she looks startled for a moment before beaming and thanking him. He's already far too used to the abnormal pattern his heart beats out by now to react to it anymore.

.

.

.

They spends hours moving from store to store; as Levi expected, Petra ends up buying many things for herself too. She drags him all over the place, far too much energy in her to be contained in such a small frame, picking out shirts and jackets and shoes for him and new heels and various articles of clothing for herself.

"You look good in this color. Really," she says when he steps out of one dressing room, feeling stupid in a silky blue-gray T-shirt. "It brings out the color of your eyes."

He wasn't aware his eyes actually had a color; he's always thought of them as a pale sort of grayish hue, not really deserving of a color. But if she says so…

The shirt is $58.

"Some sale," he grumbles, shoving it in one of the bags he's already carrying.

"It used to be $108, so quit complaining," Petra says as they leave the store. It is completely dark out now, the only lights the lamps on the sides of the streets and the storefront windows. People jostle against them as they walk; the crowds are getting bigger and bigger and there are more and more people in the outlets.

"So are we done? Can we go now?"

"Well, you _did_ get a new pair of shoes, a new jacket, a pair of khakis, and four new shirts," Petra says. "And I _did_ get a new pair of heels, a new pair of pants, two new shirts, and… what else? Oh yeah, I got a new skirt too."

Yes. She did. He remembers very clearly.

She crinkles her brow. "But wait, no, I think I should buy a pair of Uggs or something…"

His expression must be somewhat horrified (he's thinking of the vast lines outside the Ugg store) because she laughs and pokes him in the shoulder. "I'm just kidding. And I totally don't need a new bag or anything else. Yeah, let's go."

They turn for the parking lot and someone crashes into her, sending her flying into his chest. "Oof," she mumbles against the collar of his jacket. "Sorry."

"Watch where you're going, asshole!" Levi nearly yells after the guy, but Petra's right in his face, close enough that he can see flecks of gold in her eyes, her breath warm on his jaw, and he suddenly thinks it'd be so easy to just lean forward and—

_Fuck no, she's your friend, shut the fuck up!_ He moves away so quickly he nearly stumbles and trips, and stands there for a moment, willing his brain to stop spewing inappropriate thoughts at him. "You okay?" he finally manages, hoping he doesn't sound as panicked as he feels.

She's staring at him, her eyes wide, and for a moment he finds his eyes drawn to her lips, slightly parted as she looks up at him, and then he tears his gaze away and she quickly turns away too.

"Yeah, I'm fine," she says, and her voice is probably only breathless because someone just knocked the wind out of her.

That's what he repeats to himself when the incident comes back to mind later that night when he's lying in bed, and he has to tap out the rhythms of four of Beethoven's piano sonatas before he finally drifts off to sleep.

.

.

.

The morning of Mikasa and Eren's piano recital is bright and sunny, not too cold outside, no clouds marring the sky. After much deliberation, Levi decides to wear one of his new dress shirts (dark blue) instead of one of his usual white ones and the pair of khakis Petra told him to buy. He drives out to the venue early, wanting to see the program order and what other kids are playing in the recital.

He bumps into Nile Dawk, another city pianist he sees around sometimes, and nods in greeting. The older man nods back but also flinches and Levi is left wondering why he intimidates people when he's actually for once trying to be friendly.

Mikasa and Eren show up early too with their parents; Levi meets their father for the first time. Grisha Jaeger—who has a doctoral degree in music theory, apparently—shakes his hand and claims to have heard only good things about him, Carla thanks him for all the time he spent with her children, Mikasa nods at him and doesn't say anything, Eren asks him for more tips before the recital starts.

"Don't get nervous," Levi says. "Just pretend you're playing alone, the way you usually do." He's never been nervous before when playing in front of others, but he thinks it sounds like decent advice.

Hanji is already in the audience, dressed in a suit, leaning back in her chair and laughing at something the blond man next to her says. Levi narrows his eyes and walks over to them.

"What the hell are you doing here, Erwin? Don't you have a tour coming up soon? Why are you still in the States?"

Erwin's eyes spark in amusement. "Hello, Levi. I wanted to see your students play. You've rarely had students before so I couldn't pass up this chance."

"I love watching students play!" Hanji says. "Especially the same students every year. Watching their progress is amazing!"

Levi decides not to comment on how Hanji's arm is around Erwin's shoulders, or how one of her feet is on his. He checks the time on his phone and sees that it's already 1:46. "Have either of you seen Petra?"

Hanji and Erwin exchange a knowing glance and Levi resists the urge to smack them both on the head. "Well, have you?"

"No," Hanji says, "but don't worry, kid, I'm sure she'll show up."

He contemplates giving her the finger but decides against it after noticing how many children and parents are in the room. He heads to the back of the audience seats and waits, wondering if he should text Petra to see where she is or if that would seem too desperate.

Ten minutes pass, then another ten, and the recital starts. The first child to perform is one of Nile Dawk's students, a little blond girl named Annie Leonhardt. She plays a Mozart piano sonata, her fingers quick and nimble on the keys.

Even as he analyzes each student's performance, noting what is done well and what could be done better, there is a small part in the back of his mind that worries about Petra, trying to figure out why she's not here and coming up with terrible possible reasons for her absence. _Maybe she got pushed into the subway tracks by a drunk, maybe someone mugged her, maybe a tourist got overexcited and accidentally hit her on the head with his backpack and gave her a concussion and now she's in the hospital unconscious with no way of reaching anyone and there's no one to accompany her and—_

Levi tells his brain to shut the fuck up.

_Or maybe she just forgot._

It shouldn't bother him, really; he's sure she has better things to do than come to a students' piano recital. She has her own career to think of and the amount of time they've spent together in the past few months is already a lot. She probably has other business to take care of and texting him about it just slipped her mind.

It shouldn't bother him, and it doesn't. Really.

He forgets about Petra's absence for a while when Eren plays; the boy has truly improved in the last few months as well and Levi has to admit he feels proud. His tempo is relatively steady and he takes good care of the musical phrases; Levi sees the Jaegers beaming and the audience applauds heartily when Eren finishes.

Mikasa is last, and her performance is excellent, borderline perfect as usual. She gets a standing ovation from some of the more enthusiastic adults, and then the recital is over.

He goes over to congratulate his students on a successful performance; Eren thanks him profusely and even Mikasa cracks a small smile as she thanks him too. Then Carla does, then Dr. Jaeger, and then the children run off to play with some of the other children as the adult Jaegers pull him aside briefly.

"Thank you again for all your time, Mr. Stolze," Carla says, pressing an envelope into his hands. "Please accept this as a token of our gratitude."

He flicks through the envelope and realizes there are too many bills in it. "This is two hundred more than the amount we agreed on," he says, trying to hand it back, but she refuses to take it.

"No, our children have improved so much since they started learning with you, and we'd like you to have it," Dr. Jaeger says. "Also…"

Levi knows what they're going to say before they say it. "We're moving to the suburbs in Connecticut," Carla tells him. "Grisha was transferred to the Department of Music at Yale University in New Haven to be a professor there; we just got the news last week. We're afraid commuting here every week would be too much of a hassle."

Well, Levi really hasn't had any long-term students before, and he doesn't see why he should start now. This doesn't bother him either, though if he were to be completely truthful, he thinks he might actually miss the kids.

Just a little.

The Jaegers thank him for his time again and leave; Levi, for the first time that he can recall in a long time, lifts his hand to wave good-bye at Eren and Mikasa. They wave back, even Mikasa.

And then Erwin and Hanji come up to him. Hanji bumps her fist into his shoulder; Erwin nods and looks pleased. "They were great," Hanji says. "Seriously, they were amazing. You should teach more often, you grump."

"No sign of Petra?" Erwin asks.

Levi shakes his head. Erwin looks like he wants to put a hand on his shoulder but then thinks better of it. "I'm sure she had a good reason," he says. "It's nearly five now. Why don't I take the two of you out to eat?"

"Sounds good to me!" Hanji grins. "You're paying."

Levi lets his friends lead him away, and he tells himself there's no reason to be disappointed: his students did well and he doesn't have to eat his own terrible cooking tonight; but as they hail a taxi and Erwin and Hanji climb into the backseat, laughing about something, Hanji's leg brushing Erwin's, Levi thinks he's never felt more like a nonharmonic tone in his life.

.

.

.

When he finally arrives home at ten at night, just the slightest bit tipsy thanks to Erwin's generosity (or perhaps his own low alcohol tolerance), he pushes open the door to his apartment to find Petra sitting on his couch, her knees pulled up to her chest.

He stares at her for a moment, uncomprehending, and then realizes Moblit must have let her in. Hanji probably told him to.

She stares at him for a moment too; her face is pale and drawn and her eyes are downcast. "Hey," she finally says.

He shuts the door and puts his keys down on the coffee table, and sits next to her. He opens his mouth to say something—what, he has no idea—but stops short when he catches sight of her face.

Her cheeks are splotchy, bright and pale all at once, and her eyes are swollen, rimmed with red. She smiles weakly when she sees his face.

"Sorry," she says, and her voice is normal. "I've been crying a lot today."

He's terrible with comforting people, he never knows what to say or do, and he doesn't know what's wrong, if he should ask. He just looks at her and doesn't say anything.

She sighs. "I'm sorry I didn't text you. I just…"

"No, it's okay," he says quickly, and tries not to wince because his voice suddenly sounds too loud in the silence of his apartment. "I… you okay?"

_No, stupid question, she's not okay, fuck._

She laughs at that, sounding a bit more like herself, and shakes her head. "No, but I will be. I'm sorry. I just…" She takes a deep breath and releases it through her nose. "Ugh, I really should've texted you. I said I'd be there and I hate going back on my word and—"

"It's fine, really," Levi says. He doesn't mind, and if he did, he definitely doesn't anymore. Petra is bright and happy and seeing her so upset does something strange to him, like he'd do anything to see her smile again. Which, if he stops to think about it, is vaguely terrifying because he's never willing to _do anything_ for _anyone_—so he doesn't stop to think about it.

"What's wrong?" he asks.

She doesn't look at him when she says, "My mother died ten years ago today."

He feels something lurch in his stomach then, because he knows exactly how it feels to lose a mother, and with sudden clarity, he understands exactly why she's so upset.

"And," she continues, "it's not the fact that she's gone—I mean, I've had ten years to get used to that—it's because… and it's not your fault, Levi, don't blame yourself, please… it's just that every time this year I spend the day with my father or at least call him if I can't, and I always remember to at least two weeks before, but I'm so mad at myself because I just completely _forgot_; I was literally about to head out to the recital when I remembered and I can't believe I _forgot_ and how the _hell_ did I forget? She was my _mother_!"

Her voice hitches at the end and she takes another deep breath, swiping a hand across her eyes. Levi swallows something that feels like a rock in his throat.

"I mean, you're one of my best friends—seriously, you are—but she was my _mother_ and I don't know, I don't even know, and now I'm here with you. Again." She laughs again, but it is bitter this time. "I'm sorry. It's not your fault. And I'm sorry for not telling you but I was just…" She coughs and the sound is fragile, like breaking glass.

He's terrible with comforting people, he never knows what to say or do, but with Petra he doesn't think about it, just puts his arms around hers and pulls her close. It feels natural, he decides, it feels right, and she clutches him and cries and he rubs soothing circles against her back, kisses her forehead.

She fits perfectly against the crook of his neck, her eyelashes tickling his skin, her fingers digging into his shoulders, and maybe it's the tiny bit of alcohol he had that causes the thought, but he thinks he's not a nonharmonic tone after all, he's a leading tone just like he thought, and she is his tonic, warm and stable and comforting, but when there is something wrong he will be there to support her just like a leading tone should. He is a leading tone and she is his tonic, and as her tears subside and she mumbles her thanks into his shirt, he thinks he wouldn't have it any other way.

.

.

.

* * *

_A/N: Sorry if there were any errors with the theory terms or whatever; I haven't thought about the basics of theory in ages. Let me know if I got anything wrong or if things didn't make sense. Same with the non-theory terms. I don't remember my tristate area geography too well._

_Headcanon: No one killed Mikasa's parents and Eren didn't kill anyone to protect her, but she saw her parents die in the tsunami in Japan in 2011 (this story is set late 2012). Eren's always been very protective of her, especially since she gets bullied sometimes at school for being Asian/part-Asian (idk if that happens a lot anymore; I was when I went to grade school in NYC but that was over ten years ago; I was no fun though, I never cried or said anything or reacted in any way, just glared at them and they left me alone, lol)._

_**Edit:** __Sequel to this, "Rhythms of the Heart," is now out. It's been posted on my profile if you're interested._


End file.
